With agricultural harvesters, crop throughput is sensed for automatic adjustment of crop conveyance and/or crop processing devices. The crop throughput is also frequently sensed for the purpose of partial area-specific cultivation.
With the aid of a measured crop throughput, the ground speed of the harvester in a field can be adjusted by a corresponding control in such a way that a desired crop throughput is attained, which corresponds to an optimal utilization of the harvester.
A method is known for the determination of the crop throughput with corresponding sensors in the harvester (see, for example, EP 1243173 A1). Since the measurement takes place only after the crop has been taken up by the harvester, a rapid change in the crop throughput with such sensors cannot be promptly compensated for by a corresponding change of the traveling speed. As a result this can result in a low load or overload (even clogging) of the crop processing devices.
DE 10 2011 017 621 A1 proposes detecting the upper portion of a group of plants on a field by means of a laser distance sensor. The signal of the laser distance sensor also provides information regarding the density of the group of plants, since with groups full of gaps, rays penetrating to the ground result in larger variations in the traveling times and thus the evaluated distances, while dense groups give more homogeneous distance values.
Furthermore, a radar distance sensor is used. The rays of the radar distance sensor penetrate the group of plants and enable an adjustment of a ground profile. The ground profile (in combination with the measurement values of the laser distance sensor) is used to determine the height of the plants.
The intensities and traveling times of radar waves reflected from the plants are detected in order to evaluate the geometric density of the plants as well as their moisture and mass density. The “geometric density” means the volume of the plants per unit volume or area of the field.
These intensities and traveling times are used to adjust the ground speed of the harvester in a predictive manner to provide a desired mass throughput.
The system does not, however, compare the distance sensor values with others throughput sensor values that are detected on board the harvester. Therefore throughput predicted by the distance sensors is based exclusively on the measurement values of the two distance sensors (e.g. radar and laser). If these two sensors are not calibrated with sufficient accuracy for the particular group of plants to be harvested, then the throughputs calculated based on the sensor signals will be inaccurate.
DE 101 30 665 A1 describes a combine harvester with a laser distance sensor that oscillates back and forth around the vertical axis and successively scans the group of crops standing in front of the combine harvester in the lateral direction.
The traveling times of the reflected waves are detected by a receiver, which, with the aid of the traveling times and the geometric arrangement of the distance meter, determines the vertical area of the group of crops. In addition, with the aid of the intensity of the reflected waves, the volume density (space filling degree) of the crops is estimated.
The system determines the predicted throughput rate (measured in volume per unit time), by multiplying the volume density with the vertical area and speed. A moisture sensor, which views the group of crops in a predictive manner, determines the moisture of the crops so as to determine the mass density and, finally, with the aid of the throughput rate, to determine the expected mass throughput. The mass throughput, in turn, is used by the system to automatically determine an appropriate ground speed. With the aid of a measurement value, determined sensorially on board a combine thresher, using a crop throughput sensor, which, for example, detects the drive torque of a threshing drum, the throughput rate can be determined.
DE 10 2011 085 380 A1 describes another harvester with sensors which consider, in a predictive manner, the group of plants and work with electromagnetic waves, from whose signals statistical parameters are derived that are compared by sensors interacting with crops gathered by the harvester to automatically determine relationships between the statistical parameters and the crop characteristics and subsequently, to use the signals of the predictive sensors, taking into consideration the evaluated relationships for the automatic control of the harvester. The crop parameters are, among other things, the group density and the moisture. The predictive sensors can, for example, detect the intensities and polarization of the reflected waves.
The arrangements in accordance with DE 101 30 665 A1 and DE 10 2011 085 380 A1 also take into consideration sensor values obtained on board the agricultural harvester, so as to evaluate more precisely the magnitudes obtained from the signals of the sensors that work in a contactless manner, with the aid of the determined relationships.
In DE 101 30 665 A1, a correction table is produced, which corrects the crop throughputs determined with the electromagnetic sensor, with the aid of the throughputs measured on board. DE 10 2011 085 380 A1 determines relationships between statistical parameters of the crops and the detected throughputs.
In both systems, the sensor values obtained on board the agricultural harvester are thus used indirectly, in order to first convert, with them, the values of the contactless sensors into a more accurate crop throughput, which is then, in turn, used as a single regulation input magnitude for the control of the speed.
The function of the speed regulation is based on absolute measurement values of the contactless sensors, whose accuracy may not attain satisfactory results. Furthermore, the methods, under steady-state conditions, are not always accurate and as a result of the needed evaluation times of the statistical parameters, have long reaction times.
It is the goal of the present invention to provide an agricultural harvester in which the aforementioned disadvantages are not present or are present to a reduced extent.